"That may happen in 20-25 years," he said at a roundtable in Moscow on Thursday.

"If we disregard fantasies of the Mars One type, we can say there will be a flight to Mars at some point. There will be not just one flight but a whole series of them," Danilyuk said.

He said, however, the mission would be possible only if leading nations pooled their efforts. "No single country can accomplish this project on its own," he opined.

The project is very expensive, Danilyuk said. "All countries, the leaders of all countries, should unite around this wonderful idea and allot funds," he said.

In turn, head of the Cosmonaut Training Center's Space Complex, cosmonaut Alexander Lazutkin said he was not sure mankind could fly to Mars so soon. "I am very skeptical about the possibility of reaching Mars in 20-25 years. Although I wholly support this project and am ready to fly to Mars myself," the cosmonaut said.